Tierra needs 7 1/5 cubic yards of soil to fill her garden. she went to the garden store and they only had 5 1/3 cubic yards. how many more cubic yards of soil does she need to buy? i don't understand how to do this equation could i get some or tips ?

  1 13/15 cubic yards more soil

Step-by-step explanation:

If you say, "I have 3 and I need 5, how many more must I acquire?" you should be able to understand that one formulation of the problem is ...

  3 + ___ = 5 . . . . . . what goes in the blank?

You can recognize that the value in the blank is the difference between 3 and 5:

  ___ = 5 -3 = 2

The same sort of reasoning applies to the given problem, except that now the numbers are mixed numbers that include fractions. Taking the difference involves subtracting mixed numbers, but the idea is fundamentally the same.

  5 1/3 + ___ = 7 1/5

  ___ = 7 1/5 - 5 1/3

= = = = = = = = = = = = = = = = = = =

The subtraction of mixed numbers generally involves (at least) converting the fractions to ones with a common denominator. Here, that denominator will be 5·3 = 15, so the problem can be written ...

  ___ = 7 3/15 -5 5/15

Such a subtraction involves a "rewrite" somewhere along the way. Let's save that to the end, so we have ...

  ___ = (7 -5) +(3/15 -5/15) = 2 - 2/15

Now we know that 1 = 15/15 so 2 = 1 15/15 and we can rewrite the subtraction as ...

  1 15/15 - 2/15 = 1 13/15

Then ...

  ___ = 7 3/15 - 5 5/15 = 1 13/15

Tierra needs to buy 1 13/15 cubic yards more soil to meet her needs.

step-by-step explanation: